Otdfbt

I have set up an Apache Tomcat Cluster with an Apache HTTP server and load balancing on CentOS 6.6 the following way:



+ 1 VM running HTTP server & 1 Tomcat instance (used for deployment, not answering requests)

+ 1 VM running 2 Tomcat instances on different ports


Important things first:

+ watchEnabled: on master = "true", on slaves = "false"

+ HTTP connector only for master node, not defined on slaves

+ port for AJP connector different on every instance

+ tcpListenerPort for NioReceiver different on every instance

+ jvmRoute value equals respective hostname on all instances

+ path to watchDir / tempDir different, deployDir = webapps on every instance

+ port for shutdown different on every instance

+ firewalld/iptables turned off on all nodes (testing environment)

+ YES, I have read lots of things about this topic (official documentation, tutorials, etc...) already.


server.xml (only the important part)

<Server port="8004" shutdown="SHUTDOWN">
 <Service name="Catalina">
 <!-- HTTP connector on port 8081 -->
 <Connector 
 connectionTimeout="20000" 
 port="8081" protocol="HTTP/1.1" 
 redirectPort="8443"/>
 <!-- Define an AJP 1.3 Connector on port 8012 -->
 <Connector 
 port="8012" 
 protocol="AJP/1.3" 
 redirectPort="8443"/>
 <!-- Engine definition for clustering -->
 <Engine 
 defaultHost="localhost" 
 jvmRoute="acd10-master" 
 name="Catalina">
 <Realm className="org.apache.catalina.realm.MemoryRealm"/>
 <Host 
 appBase="webapps" 
 autoDeploy="true" 
 name="192.168.2.139" 
 undeployOldVersions="true" 
 unpackWARs="true">
 <Cluster 
 channelSendOptions="6" 
 className="org.apache.catalina.ha.tcp.SimpleTcpCluster" 
 useDirtyFlag="true">
 <ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/>
 <Valve className="org.apache.catalina.ha.tcp.ReplicationValve" filter=""/>
 <Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve"/>
 <Channel className="org.apache.catalina.tribes.group.GroupChannel">
 <Membership 
 address="228.0.0.4" 
 className="org.apache.catalina.tribes.membership.McastService" 
 dropTime="3000" 
 frequency="500" 
 port="45564"/>
 <Receiver 
 address="auto" 
 className="org.apache.catalina.tribes.transport.nio.NioReceiver" 
 maxThreads="6" 
 port="4005" 
 timeout="100"/>
 <Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">
 <Transport 
 className="org.apache.catalina.tribes.transport.nio.PooledParallelSender"/>
 </Sender>
 <Interceptor 
 className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/>
 <Interceptor 
 className="org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor"/>
 <Interceptor 
 className="org.apache.catalina.tribes.group.interceptors.ThroughputInterceptor"/>
 </Channel>
 <Deployer 
 className="org.apache.catalina.ha.deploy.FarmWarDeployer" 
 deployDir="/usr/local/tomcat7/webapps/" 
 tempDir="/usr/local/tomcat7/war-temp/" 
 watchDir="/usr/local/tomcat7/war-watch/" 
 watchEnabled="true"/>
 </Cluster>
 </Host>
 </Engine>
 </Service>
</Server>

mod_proxy.conf

<VirtualHost *:80>
 DocumentRoot /var/www/html

 ProxyRequests Off
 ProxyPreserveHost On

 <Proxy *>
 Order deny,allow
 Allow from all
 </Proxy>

 <Proxy balancer://testcluster>
 BalancerMember ajp://192.168.2.166:8010/ route=acd11-node01
 BalancerMember ajp://192.168.2.166:8011/ route=acd11-node02
 ProxySet lbmethod=byrequests
 </Proxy>

 # Exclude balancer-manager app to make it available on master
 ProxyPass /balancer-manager !

 ProxyPass / balancer://testcluster/ stickysession=JSESSIONID|jsessionid
 ProxyPassReverse / balancer://testcluster/ stickysession=JSESSIONID|jsessionid

 <Location /balancer-manager>
 SetHandler balancer-manager
 </Location>
</VirtualHost>

EDIT:

Apache error log (what it gives me after startup):

[Tue Jan 06 08:29:49.235859 2015] [mpm_prefork:notice] [pid 9655] AH00170: caught SIGWINCH, shutting down gracefully
[Tue Jan 06 08:29:50.306520 2015] [core:notice] [pid 9727] SELinux policy enabled; httpd running as context system_u:system_r:httpd_t:s0
[Tue Jan 06 08:29:50.307867 2015] [suexec:notice] [pid 9727] AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
[Tue Jan 06 08:29:50.319218 2015] [so:warn] [pid 9727] AH01574: module proxy_module is already loaded, skipping
[Tue Jan 06 08:29:50.319797 2015] [so:warn] [pid 9727] AH01574: module proxy_ajp_module is already loaded, skipping
[Tue Jan 06 08:29:50.319827 2015] [so:warn] [pid 9727] AH01574: module proxy_balancer_module is already loaded, skipping
[Tue Jan 06 08:29:50.320610 2015] [so:warn] [pid 9727] AH01574: module proxy_http_module is already loaded, skipping
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using fe80::50a0:e2ff:fe74:5294. Set the 'ServerName' directive globally to suppress this message
[Tue Jan 06 08:29:50.328101 2015] [auth_digest:notice] [pid 9727] AH01757: generating secret for digest authentication ...
[Tue Jan 06 08:29:50.329387 2015] [lbmethod_heartbeat:notice] [pid 9727] AH02282: No slotmem from mod_heartmonitor
[Tue Jan 06 08:29:50.333216 2015] [mpm_prefork:notice] [pid 9727] AH00163: Apache/2.4.6 (CentOS) configured -- resuming normal operations
[Tue Jan 06 08:29:50.333263 2015] [core:notice] [pid 9727] AH00094: Command line: '/usr/sbin/httpd -D FOREGROUND'

What I try to achieve:

We have many enterprise web applications which we wanna load balance throughout a Tomcat farm.


What does work:

+ Tomcat clustering

+ Replication

+ FarmWarDeployer


What doesn't work:

Whenever I try to call an application that's been deployed throughout the cluster, it gives me 404 not found. Same for Tomcat root applications such as /manager/html or /host-manager. Only application that is working is /balancer-manager, obviously.



The httpd server is supposed to serve as a load balancer and proxy to the tomcats. It will have to deliver some static content but first and foremost, I need to get this thing up and running to load balance the JavaEE applications (servlets). AJP to the cluster nodes is a must have for me, since http access must not be allow (+ for some other reasons that are worth a totally different discussion).


Since everybody seems to set up the mod_proxy configuration in a different manner, I am looking for a straight forward solution that gives me something I can build on. If you need more information or more configuration details, let me know and I will provide you with those. I already have a second cluster configured using mod_jk and everything is working as intended, but the Stakeholders require this mod_proxy(_ajp) thing and it just grinds my gears.



Your help is much appreciated!

Best regards!

I haven't tried reproducing your configuration but when I looked at it this morning, it looks like the problem is simply a missing space and possibly the ProxyPassReverse not matching the ProxyPass (however the later wouldn't give you a 404 I think).

ProxyPass / balancer://testcluster/stickysession=JSESSIONID|jsessionid

ProxyPassReverse / balancer://testcluster/

should be:

ProxyPass / balancer://testcluster/ stickysession=JSESSIONID|jsessionid

ProxyPassReverse / balancer://testcluster/ stickysession=JSESSIONID|jsessionid

At least, that's how I have mine and I have no issue (but I don't use AJP, just regular http proxy).

Obviously this is assuming all the basic stuff are in place (site enabled, reload, http proxy mod installed and enabled, etc).